What Is a Lookalike Audience in Facebook Ads

Short answer

A lookalike audience is a Facebook ad targeting option that finds new people who share characteristics with a source list you provide — such as your existing customers or email subscribers. Facebook analyses the source list, identifies patterns, and finds millions of similar users to show your ads to. It typically outperforms interest-based targeting for businesses with enough customer data.

How lookalike audiences work

1. You provide a source audience — a custom audience built from your customer list, website visitors (via Facebook Pixel), or page engagers
2. Facebook analyses that source for common demographics, interests, and behaviours
3. Facebook finds a larger group of similar users in your target country
4. You choose the audience size: 1% = most similar; 10% = broader reach

A 1% lookalike of 1,000 customers in the UK gives you roughly 500,000–600,000 people who closely resemble those customers.

What you need to create one

• A source audience of at least 100 people (Facebook recommends 1,000–50,000 for best results)
• A Facebook Business Manager account
• The Facebook Pixel installed on your website (for website-visitor lookalikes)

The best source audiences for lookalikes:

• Your customer email list (highest quality — these people already bought)
• Website visitors who reached the checkout or thank-you page
• Video viewers who watched 75%+ of a video

When lookalike audiences work best

Lookalikes work well when:

• You have at least 500 source customers (more data = better pattern recognition)
• Your existing customers are genuinely satisfied (you want Facebook to find more of the same)
• You're scaling an offer that already converts cold traffic

Lookalikes work poorly when you're just starting out with no customer data, or when your source audience is too small and mixed.

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